Understanding the flowering stage
Female flowers, buds, pollen and seeds
Female cannabis plants produce flower clusters containing bracts and pollen-receptive stigmas (the fine hairs often called pistils). Photoperiod-sensitive varieties respond mainly to day length and uninterrupted darkness; switching lamp technology or fertilizer does not by itself trigger flowering. Autoflowering varieties follow a different pattern.
Without successful pollination, female flowers generally develop without mature seeds. The familiar term sinsemilla refers to seedless cannabis flower.
Pollen from male flowers can fertilize female flowers, leading to seed production. Pollination changes the plant's reproductive development; it does not simply turn buds into a different plant.
For a detailed flowering timeline, use the flower anatomy and week-by-week guide. For the underlying biology, see flowering light cycles and male versus female plants.
From the original grow archive: the photographs and equipment references below document an earlier growing setup. Bulb swaps, prescribed fertilizer changes and a fixed flowering duration are not universal requirements.
Flowering Marijuana Plants for Buds indoors or Outdoors, cannabis plants flower in the fall when days become shorter and when the marijuana plant signals itself that annual life is at its end. In this archived indoor grow, we described how marijuana flowering was managed using the original setup's growing nutrients, grow light bulbs, and the hours of light the marijuana plants receive each day. During flowering, leafy growth slows and marijuana flowers begin to form. Flowers without seeds are known as marijuana buds and better known as sinsemilla. If a male cannabis plant is in the grow room and its pollen is exposed, it will find its way to your female plants and pollinate it creating cannabis buds filled with seeds. Knowing when to flower your cannabis or marijuana plants is very important, otherwise you will end up with low quality buds.
Flowering Marijuana for Buds
After you have pre-flowered your plants to determine their sex, its time to decide if you want to flower females for buds or if you want to flower males for pollen and cross-breeding. Female plants are known for their heavy, potent flowers filled with resin. The best strains for indoor growing are the ones that stay short and bushy with branches close together, creating denser buds and requiring less space to be grown in. Many photoperiod cannabis cultivars flower under a roughly 12-hour light and 12-hour uninterrupted dark schedule; autoflowering varieties do not rely on the same daylight trigger. In this earlier setup, the grower changed the nutrients and the lights from Mini Sunburst Metal Halide 175w w/ Lamp(paid link)
to Hydrofarm 1000 Watt HPS Radiant Economy Grow Light System(paid link). Most strains will show signs of flowers within 2 weeks of being introduced into flowering. The flowers will appear near the top of the plant, pale hair-like stigmas may become visible. Flowering duration varies with genetics and conditions; nine weeks is not a universal timeline. Once your plants are done flowering you will need to harvest them. My videoshows you step by step on how to do this.
Flowering Marijuana for Seeds
Male Cannabis Plants flower approx. 1-2 weeks before females. When male plants flower they release pollen, which will find its way to a female, creating buds filled with seeds. If you do not want seeds you need to remove the plant as soon as it shows signs of being a male. If you are choosing to cross-breed, you will want to have female plants in the room you are using for flowering marijuana.